Background

This report provides a brief summary of the weekly ensemble forecast for Michigan from the COVID-19 Forecast Hub. In collaboration with the US CDC, our team aggregates COVID-19 forecasts from dozens of teams around the globe. Typically on Wednesday or Thursday of each week, a summary of the week’s forecasts from the COVID-19 Forecast Hub appear on the official CDC COVID-19 forecasting page.

Every week, teams submit their forecasts to the COVID-19 Forecast Hub.

Each Tuesday, we combine the most recent forecasts from each team into a single “ensemble” forecast of reported COVID-19 cases at the county, state, and national level and deaths at the state and national level. At the moment, we only generate ensemble forecasts for four weeks into the future, as we don’t have reliable evidence that the models are accurate past that horizon.

Weekly reports from the COVID-19 Forecast Hub can be found at this page. We expect that these reports will become more detailed as the weeks go on.

COVID-19 Mortality Forecasts

Since the inputs to the ensemble model do not factor in changes in behavior or policy that could have an impact on short-term disease transmission (e.g. school openings or closures, new interventions, governmental policy shift, etc…), the ensemble model itself should not be looked to for specific answers to questions like “what will happen if or when schools open in 2 weeks” because most of the input models are not factoring in these changes. That said, the ensemble model has consistently shown strong predictive performance, and very few of the many interventions put in place appear to have created dramatic changes in short-term disease transmission.

State level

This week, our ensemble combined forecasts for Michigan from 44 different models.

At the state level, the ensemble model’s best guess is that we will see between 260 and 350 deaths each week for the next four weeks with around 16,700 deaths by February 27 (Figure 1). However for the week ending February 27, the ensemble shows substantial uncertainty, with observed deaths between 80 and 520 deemed possible (95% prediction interval: 82 - 517).

During periods of relative stability, models in general show broad agreement about the predicted trajectory of the outbreak. However, when there are steep surges or declines in cases or deaths, models often have quite different predictions for the upcoming weeks. The result is that there is increased uncertainty in the ensemble forecast, which can be seen as wider confidence intervals in the forecast visualization. You can explore the full set of models, including their forecasts for past weeks online at our interactive forecast visualization.

Figure 1: Weekly observed and forecasted COVID-19 deaths. Observed data from JHU CSSE and forecasts from the COVID-19 Forecast Hub.

Figure 1: Weekly observed and forecasted COVID-19 deaths. Observed data from [JHU CSSE](https://github.com/CSSEGISandData/COVID-19/tree/master/csse_covid_19_data/) and forecasts from the [COVID-19 Forecast Hub](https://covid19forecasthub.org/).

For state-level death forecasts made over the last 6 weeks in Michigan for which observed data are now available, the 95% prediction intervals covered the truth 100% of the time, and the 50% prediction intervals covered the truth 44% of the time.

The sortable and searchable table below shows the total number of reported COVID-19 deaths at the US level and for Michigan over the last two weeks (January 17, 2021 to January 30, 2021) and the forecasted counts for the subsequent two weeks (January 31, 2021 to February 13, 2021).

COVID-19 Incident Case Forecasts

State level

At the state level, the ensemble model’s best guess is that we will see between 8,700 and 11,600 cases each week for the next four weeks (Figure 2). However for the week ending February 27, the ensemble shows substantial uncertainty, with observed cases between 1,800 and 20,083.

You can explore the full set of models, including their forecasts for past weeks online at our interactive forecast visualization.

Figure 2: Weekly observed and forecasted COVID-19 Cases. Observed data from JHU CSSE and forecasts from the COVID-19 Forecast Hub.

Figure 2: Weekly observed and forecasted COVID-19 Cases. Observed data from [JHU CSSE](https://github.com/CSSEGISandData/COVID-19/tree/master/csse_covid_19_data/) and forecasts from the [COVID-19 Forecast Hub](https://covid19forecasthub.org/).

For state-level case forecasts made over the last 6 weeks in Michigan for which observed data are now available, the 95% prediction intervals covered the truth 10% of the time, and the 50% prediction intervals covered the truth 55% of the time. The truth tended to be lower than the prediction interval.

The sortable and searchable table below shows the total number of reported COVID-19 cases at the US and state level for Michigan as of Saturday, January 30, 2021 (“Total COVID-19 Cases”), as well as the weekly case count and rate of reported COVID-19 cases in the population (standardized per 100,000 population) over the last week (January 24, 2021 to January 30, 2021) and two weeks ahead (February 07, 2021 to February 13, 2021).

When interpreting probability of an increase, it’s important to note that the increase or decrease is relative to the location-specific recent observed incidence, which varies across locations.

County level

This report was reproducibly and dynamically generated using RMarkdown. The code for the report can be found here.